No problem Stevo. Hang out here and you'll soon be an RC addict with a lot of knowledge. There are a lot of guys here that have been into the hobby for a long time. My first experience with hobby grade stuff was around 1980 when my dad got into flying RC planes. Been hooked ever since.
There are parts on RC cars that are prone to breakage, because there needs to be some flex in areas to absorb some impact. Like the A-arms. You want to stick with plastic there so they take the hit and flex to absorb it. But things like carriers, spindles, bulkheads, shock towers - those can be...
If you hit anything hard enough, anything will break. But if you hit a wheel, the A-arm will flex, absorbing the impact. If the plastic bulkheads gave way before the A-arm, I would say they are cheap, weak ass plastic. So an aluminum upgrade will solve that. Replacing an arm is a lot easier than...
If by suspension holder you mean shock tower, then yeah, going aluminum will be just fine. That being said though, having an aluminum rear shock tower on my Jato caused it to do some major damage to the car on a very, very light bump on the rear on s bad landing, but the Traxxas Jato...